The goal of the radiographic program is to determine the rate of mineralization of bone regeneration under membranes in a monkey model and to determine the effects of implant loading on the changes in newly regenerated bone in vivo. Correlations between the clinical, radiographic, biological and biomechanical aspects of bone regeneration and loading with implant will be made. In the first funding period algorithms for the measurement of changes in bone height and mass using quantitative digital subtraction radiography in the monkey were successfully developed, validated, and used to study implants over time in vivo. The radiographic program will use quantitative radiographic data to: (1) determine the rate of mineralization of regenerated bone in the monkey model as determined radiographically, (2) correlate the kinetics and magnitude of growth factor expression in regenerated bone and extraction sites, (3) correlate the expression of growth factors and cytokine release under exposed membranes, (4) determine the radiographic rate of bone change around root-form titanium implants placed in the regenerated bone and to compare this rate of bone change to the historical data for titanium implants previously placed in the same sites and to correlate the radiographic changes with the clinical course, microbiology, and histology of these sites. Radiographic changes will be correlated with the histology in fresh extraction sites and in trabecular bone. This program also will further develop the digital radiographic techniques, so that subtraction radiography can be performed more easily with less time spent per radiographic pair analyzed. Computationally simple algorithms, that will automatically select reference points on subsequent radiographic examinations for affine or rubber sheet transformations to correct small planar geometric discrepancies, will be developed and validated.